1. Field
The present disclosure relates to image sensors, such as image sensors having an improved light utilization efficiency, by using a color separation element and a color filter.
2. Description of the Related Art
A color display apparatus or a color image sensor generally displays images of various colors or detects colors of incident light by using color filters. In a current color display device or a color image sensor, an RGB color filter mechanism is most popularly employed, in which, for example, green filters are arranged at two of four pixels and a blue filter and a red filter are respectively arranged at the other two pixels. Furthermore, other than the RGB color filter mechanism, a CYGM color filter mechanism may also be employed, in which cyan, yellow, green, and magenta color filters (complementary colors) are respectively arranged at four pixels.
However, a general absorption-type color filter absorbs lights of colors other than its own color, and thus light utilization efficiency may deteriorate. For example, in the case of using RGB color filters, only one-third of incident light is transmitted and two-thirds of the incident light is absorbed. Thus, light utilization efficiency is only about 33%. Therefore, in a color display apparatus or a color image sensor, most light loss occurs in color filters.
Recently, to improve light utilization efficiency of a color display apparatus or a color image sensor, there have been attempts to use a color separation element instead of color filters. A color separation element may separate colors of incident light by using a diffraction characteristic or a refraction characteristic that differs based on wavelengths, and colors separated by using the color separation element may be transmitted to pixels corresponding to the colors, respectively. However, a color separation element is still unable to provide images that are as clear as images provided by using color filters.